In some water supply systems, contaminated water from plumbing fixtures, such as urinals and toilets, may enter back into the main water supply if a vacuum is drawn on the main supply (e.g., when a fire hose is supplying water from a fire hydrant during a fire). Vacuum breakers are used in these systems to prevent back-siphonage of the contaminated water into the main supply.
Typically, vacuum breakers are installed into an outer tube of a flush valve as described in U.S. Pat. No. 7,802,586 ('586 patent) issued to Zurn Industries, LLC, the entire disclosure of which is hereby incorporated herein by reference. As shown in the '586 patent, the outlet tube of the flush valve includes circumferentially spaced air slots which enable air to flow through the vacuum breaker, as opposed to water, in the event of a vacuum being drawn on the main supply.
Currently, bathroom plumbing equipment (e.g., toilets, urinals, or other plumbing equipment) is moving towards using a lower volume of water per flush at a higher pressure. While this low volume, high pressure strategy may be more efficient, it can introduce a back pressure on the vacuum breaker and test the mechanical durability of the vacuum breaker under the most extreme conditions. The increased back pressure on the vacuum breaker may cause water to leak past the vacuum breaker and out the air slots.
Hence, a need exists for a vacuum breaker that seals during increased back pressure conditions, and provides structural durability at or near the air slots of the outer tube.